This work describes a high performance and reliable deep submicrometer n-channel metal oxide semiconductor field effect transistor (n-MOSFET) with ultrathin gate oxide prepared by combining nitrogen gate electrode implantation and native-oxide-free in situ HF vapor preoxidation cleaning. The results herein reveal that the performance and reliability, including the leakage current of the ultrathin gate oxide, charge-to-breakdown, drain current, transconductance, charge pumping current, stress induced leakage current, and hot carrier reliability of n-MOSFETs are all significantly improved. The enhanced reliability and performance are attributed to the native-oxide-free process, smooth interface, and reduced incorporation of As in the gate oxide which results from HF vapor cleaning and nitrogen implantation.